• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Antibiotic Sensitivity Test

Extracts from this document...

Introduction

Antibiotic Sensitivity Test Introduction Antibiotics are used to treat bacterial infections. They either kill the bacteria or prevent them from multiplying. They do not however have any effect on viruses. The first antibiotic was discovered accidentally in 1928 by a Doctor Sir Alexander Fleming. He left the lid of a petri dish and discovered some unusual fungus growing in it. He noticed that where the fungus grew the bacteria had ceased to exist. He reasoned that fungus must kill the bacteria and identified the substance as Penicillium notatum. It wasn't until 1940 that Howard Florey discovered a way to make the drug useful for humans. The majority of antibiotics that we use today are natural products that are made in large quantities in enormous vats by fermentation, there are however some antibiotics which are made synthetically. Aim The aim of the experiment was to test the effect of eight antibiotics on the bacterium Staphylococcus albus. ...read more.

Middle

Allow the nutrient agar to cool and set. Step 4 Once set, using a sterile pair of forceps, place the Mastring disk onto the set agar and replace the lid. The Mastring disk is a paper disk with 8 coloured disks attached to it. These 8 disks are impregnated with a known antibiotic. (See Picture 1 below) Picture 1 Photo of Mastring being used in Antibiotic Sensitivity Test Control Dish 2 An identical dish was set up using steps 1-3 as above. This will be a control dish to compare S. albus growth with and without antibiotics present. Control Dish 3 A third dish containing 25cm of sterile nutrient agar only was set up also as a control. This control will check that the agar was sterile and that the aseptic technique was carried out correctly. Once the agar had set in all 3 petri-dishes, seal with tape and turn upside down to prevent condensation forming on the plates and incubated for 48 hours at 25C. ...read more.

Conclusion

Conclusion The most effective antibiotic to inhibit S. albus was Tetracycline as the clear area was very well defined. Some of the other antibiotics were not as effective, the clear area was not so well defined and in some cases the areas overlapped and made it difficult to measure there effect accurately. The result did support the hypothesis. Control Dish 2 was cloudy in appearance, which indicated a uniform growth of S. albus, throughout the agar. This suggests that the agar had been prepared correctly to enable the growth of the bacteria. (See diagram 5) Control Dish 3 was completely clear, which indicated no growth of micro organisms and that the aseptic technique was carried out correctly. (See diagram 5) Further Work A different bacterium could be used to observe whether the same antibiotic was as effective as on the S. albus. The same bacteria could be used but isolated with just one antibiotic to get a clearer result. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our GCSE Living Things in their Environment section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related GCSE Living Things in their Environment essays

  1. Marked by a teacher

    Research question - Is using dogs for work ethical?

    5 star(s)

    (2) * Hunt foxes (3) * Fight (3) * Race (3) * Help life-guards to rescue (1) * Speak (2) * Guard dogs (1) * Therapy dogs (entertainment for those people who cannot move freely) (1) * Tracking dogs (find lost people) (1) I believe that not all of these tasks are ethical because some

  2. Marked by a teacher

    A2 Biology Coursework -Investigation into the effect of different concentrations of antibiotics on the ...

    4 star(s)

    If these bubbles were in the bacterial solution, it would have decreased the amount of bacteria present in it resulting in a lower light absorbency reading and vice versa with the antibiotics. (This would result in a lower amount of antibiotic meaning a reduced amount of bacteria may have been killed because of this resulting in a higher absorbency value.)

  1. Investigation - Examination of bacterial sensitivity on antibiotics.

    bacillus and micrococcus. (xv) Finally when the results are ready, place the dish on a piece of graph paper and use the squares to measure the diameter of the clear area. (xvi) After sealing the dish, incubate it for 2 to 3 days between 25 to 30 degrees centigrade. (d)

  2. Investigating the effect of four antibiotic agents on gram positive and gram negative bacteria.

    The stage in translation that Streptomycin inhibits is shown below: Streptomycin is an odourless off-white powder and is bitter to taste. It is effective against gram-negative bacilli as well as many cocci. The antibiotic is also used against tubercle bacilli and is included in a combination of other drugs to treat tuberculosis.

  1. Extended Experimental Investigation - Natural Antibiotics

    while lawning - Loose hair tied up - Check 'ChemWatch' for risks of substances used (find attached) - Sterilize inoculating loops and forceps immediately - Immediately dispose of agar plates when finished observations Method 1. Sterilize bench or other working area with methylated spirits.

  2. The comparison of bacterial content in a range of milks.

    Risk of pathogenic bacteria being produced-when the bacteria are replicating on the agar plates the temperature must be kept bellow 30�c and the plate must be sealed and never opened. 11. Follow aseptic techniques (these can be found in the method and the safety precautions bellow)

  1. An investigation into the antibiotic effects of penicillin and streptomycin on the bacterium Escherichia ...

    coli is one of the bacilli bacteria and measures 1-2 �m in length and 0.1-0.5 �m in diameter. When a gram stain is performed on E. coli it comes up as a gram negative bacteria. Gram-staining is the primary method of identification of bacteria(B), and is a technique carried

  2. The effect of osmosis on potatoes

    This will give me a varied set of results from which I hope to make a decent conclusion. If any of the non-variables below are not kept constant it would mean it would not be a fair test. For instance if one of the potato chips was 1cm longer the

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work